Who is more willing to use a smartphone app to promote sustainable travel behavior?

In the last decade, there has been growing interest in Voluntary Travel Behavior Change (VTBC) programs that use smartphone applications to encourage people to shift from car use to more sustainable transportation modes. However, most of these programs have used small and distorted sample sizes, making it unclear who are the individuals who choose to download and use such apps. To address this gap, in the current study we investigate which objective and subjective factors could influence individuals' intention to use a VTBC application designed to promote sustainable mobility, while also examining the interplay between this intention and current travel habits. To analyze these relationships, we developed a joint Integrated Choice and Latent Variable (ICLV) model that simultaneously considers two choice dimensions: (1) current commuting mode choice, and (2) intention to adopt the VTBC application. Our analysis uses data from 3044 commuters who were invited to take part to a VTBC program in the Cagliari metropolitan area (Italy). At the aggregate level, 44.1 % of respondents expressed interest in using the VTBC application. The modeling results reveal that individuals with graduate education, monthly incomes below €2000, and bicycle ownership demonstrate higher likelihood of app adoption. Among psychological factors, Environmental Concern and Attitude toward Sustainable Mobility positively influence the intention to use the application. As far as the interaction with mode choice is concerned, public transit users show stronger intention to adopt the application. Notably, some of the variables influencing app adoption intention differ from those affecting commuting mode choice, suggesting these represent distinct behavioral processes. These findings have important policy implications, emphasizing the need to carefully consider the promotion of such to engage as many people as possible. Additionally, extra caution is required when interpreting the results of these programs and their generalizability to the entire population, due to the self-selection of participants.